c6mekl is a multi-temperature
mekal model using sixth-order Chebyshev polynomial for the differential
emission measure. The DEM is not constrained to be positive.. The switch
parameter determines whether the mekal code will be run to calculate the model
spectrum for each temperature or whether the model spectrum will be
interpolated from a pre-calculated table. The former is slower but more
accurate. The reference for this model is Singh et al. (1996, ApJ, 456,
766).

c6pmekl differs by using the
exponential of the 6th order Chebyshev polynomial

c6mekl
and c6pmekl use abundances relative to the Solar abundances set by the abund
command

The variants c6vmekl and c6pvmkl
with polynomial and exponential polynomial respectively allow the user to
specify 14 elemental abundance.